Injection molding processes require heating a mold surface to temperatures near the injection temperature of the polymer. This is accomplished by conducting heat to the mold surfaces using an internal and/or external source of heat. This process involves surface temperatures of the polymer part that exceed ejection temperatures of the part. Thus, it is necessary to cool the mold and the molded part prior to ejecting the part. However, heating and cooling the mold lengthens the cycle time, which decreases production efficiency. In addition, due to the high pressure that can be required in some processes, high strength materials, such as steel, are used to form the body of the mold. Thus, the molding cycle is also limited by the heat transfer through the material of the mold body. Also, complex three dimensional mold surfaces can result in uneven or non-uniform surface temperatures. The temperature gradients create hot and cold spots on the mold surfaces, which can negatively impact the surface appearance of the molded polymeric part and contribute to a longer cycle time.
Accordingly, there is a need for a mold and method of molding a polymeric part that is capable of employing complex mold surface geometries while producing uniform surface temperatures and reducing the heating and cooling rate. Also, there is a need for a molding apparatus that is capable of withstanding high mold pressures.